Colloidal suspension



.1. meted sea-1 19.41-

, 2,231.32: 7 comma susrnusron Ogden Fitz Simona Warren, .Pa., acaignor to Floridi'n Company, Warren, Pl a corporation ofDelawa i-e No Drawing.

Application'hl'ovember 20, 1940, .Sfllll No; 366.476

' notices. (01. 255-1) The present invention relates to anew and improved method of producing a colloidal clay suspension which maybe used'as a drilling mud and for various other purposes. The application is a 5 continuation-impart of my allowed copending application SerialNo. 128,027, filed February 26,

In the drilling of wells, the cuttings released by the drill are usually removed by introducing 'drilll ing mud into the well. This fluid must have several properties; e. g., a high viscosity, so as to carry with it the rock cuttings from the well, and also so that it will hold in suspension various weighingmediums, such as finely ground barytes or iron oxide. It should also possess thixotropic properties; that is when circulationis stopped,

the fluid must form a gel so that the cutting al-" ready in suspensionwill not settle out, for exam.- ple, during periods when the bit is being changed. Various methods and means have heretofore been employed for providing an aqueous mixture to-remove the cuttings from wells through which the drill is bored. Thus,in the Cross et al. Patent 2,044,758, dated June 16, 1936, there is disclosed an aqueous suspension composition which includes a brine having suspended therein from one to ten percent of fullers earth of the Florida- Georgia type. This atent states that the composition may .be mixed by the apparatus and method of dispersing particles as shownfin the Cross Patent 2,044,757, dated June 16, l936. It will be 'noted that in the Cross apparatus it is necessary either to shipthe bulky drilling mud in the water suspension to the well or to install an apparatus at "the well for the production of, this suspension.

An important object of thepresent invention is to provide a simple, efllcient and economical method of producing a colloidal clay suspension which may be used with or without a saline material or brine, and which may be produced at the well from dry earth with minimum expenditure of time and labor.

If fullers earth is dried at a low temperature and. then reduced to granular form and placedin water, this mixture will slime slightly on the upper surface or outside, but will retain its granular structure unless subjected to high speed mixdng 5 for an extended period or passing the suspension through a colloid mill .or letting the suspension under high pressure, or other drastic treatment.

In my improved method of producing a colloidal clay suspension, the moist, natural fuller's earth another is readily determinable.

before being dried, so as to be subjected to pres-i sure suiiloient to rupture the original structure ofthe clay and thus cause each particle to move or slip to anew position relative to the other col-' loidal. particles. The suiliciency of the pressure 5 v in respect to rupturing the clay structure and causing movement of the particles relative to one I While this pressure may vary with difierent clays, it. can be determined in respect to any particular clay by 10' comparison of the viscosity of a colloidal suspension prepared from the extruded clay as compared to the viscosity of the same percentage of suspension produced from the same clay which has not been extruded. The fuller's earth is sub- 1 jected to pressure suflicient to rupture the original structure of the earth. Ordinarily, this can be accomplished by extruding the earth through an auger-type extrusion machine-under a pressure substantially in excess of'100 pounds per 20 square inch as measured at the die plate. A suitable apparatus for subjecting the earth to extrusion pressure is illustrated, for example, in the patent toHartshorne No. 2,079,854, granted May 11, 1937. It will, of course, be manifest thatthis pressure may vary in accordance with the particular kind of clay being worked.

I have found, that ordinarily extrusion pressures ranging from 100 up to 500 pounds per.

square inch give quite satisfactory results and that pressures substantially in excess of 600 pounds per square inch are not justified; since the improvement obtained is small, compared with the increased cost. The most eonvenienttype of pressure treating equipment is an auger extrusion machine of the character disclosed in the above identified Hartshorne patent. In such a niachine, using: a clay of uniform consistency, presv sures are ordinarily controlled or regulated by the number and size of the.openings in the die plate andby the thickness of the die plate. When thepressure is increased by decreasing the size or.

.number of the openings,'or by thickening the die 7 plate, increasing percentages of the clay flow back between the auger and the wall of the extrusior cylinder until finally a point can be reached where little or no flow of material is used. a from the machine. It is obviously desirable, therefore, to regulate thepressure so that while 5 obtaining the result desired, there is a suitable flow from the machine. a p

It is believed that the ultimate particles of Florida-Georgia fullers earth have one-or more dimensions vastly greater thanthe other dimen- 55.

other theories to bundles of fiat plates, are held together by varying degrees of cohesive force. By subjecting the earth to extrusion shearing forces, the bundles are slipped or broken apart along various shear planes. It is desirable to use pressures which will cause sufiicient shearing to substantially enhance the colloidal properties of the earth and generally speaking the higher the pres-- sure, the larger the number of shear-planes that are formed. I find that generally subjecting Florida earth containing in the neighborhood of 52% free water to pressures of from 50 to 300 pounds per square inch effects a very substantial enhancement in the earth's colloidal properties.

The pressure treated clay is then dried preferably at temperatures substantially below 600 F. and reduced to the desired granular form. In

fact, the best results are obtained when this ma- "terial is dried at temperatures around 200 F. The granulated clay is then placed in water in proper proportions of each, depending upon the character or type of-the clay and the particular constituents of the'earthy material where the well'is to be drilled. Granulated 'clay so treated will slake readily when mixed with water. so that a-satisfactory supension is obtained by less drastic in preparing drilling muds from-Fiorida-Georgia iullers earth but simple grinding-is suflicient,

.thereby effecting a considerable saving in grinding costs. The colloidal suspension thus formed constitutes a smooth, viscous non-fiocculant,

gelatinous mixture in which the colloidal particles are free from agglomeration or agglutination.

To this mixture may be added, if desired a suitable brine or salts as a medium of producing a stable clay suspension.

I have found that the clay maybe extruded and then subsequentl dried and when resuspended in water, certain original advantages of extrusion are maintained. While it would be expected that on drying, the eflect of extrusion would be lost, it is an unexplained fact to find that this is not the case and that an unexpected improved result is efiected due to the fact that a higher percentage of earth particles are separated on material that has been previously extruded and dried as compared to material that has not been so treated.

It might be noted that the lower the temperature of drying, the more gel-like is the emulsion or suspension that is formed. Moreover, the lower the temperature, the less combined moisture is removed from the clay and thus the more gellike the suspension that is subsequently formed when the water is added to the clay. Consequently, as indicated in the example hereinafter given, I prefer temperatures very substantially below 600 F. Although diflerent earths will react somewhat difierently to temperatures between 100 F.-

and 600 F., it is preferable that the temperature treatment be nearer 100 F., as shown in the following example, than 600 'F.

For most earths of the Georgia-Floridatype from which are produced 6% suspensions, for example, I find that the optimum drying temperature is in the neighborhood, of 200 F., and that when the temperature substantially exceeds 250 F., there is a marked andrapid decrease in the eflect obtained by extrusion. Consequently, it is desirable that the temperature of drying be substantially below 600 F., and in the neighborhood of 200 F. if one is to avoid'sacrificing the advantages of extrusion. At 600 F. a gel-like emulsion is' no longer. obtained when the clay is suspended in water, and once .the material is dried at temperatures in excess of 600 F., there is no way to make the action reversible and obtainthe gel which had been destroyed by heating to this temperature.

I have found that if the clay is pressure treated by extrusion before drying, it not only will break down into a colloidal suspension from a granular form, but even when ground to a fineness in excess of 200 mesh (200 openings per linear inch) it will produce a more efilcient colloidal suspension than can be obtained by untreated clay, similarly ground. As an example, two samples of fullers earth were taken from two different mines at Quincy, Florida, and a portion of each was extruded. All four samples were then dried under a hot air blast at F. and reduced to pass 200 mesh. A mixture was then .made up in a 4% solution and the viscosity determined in a Stormer viscometer. with a 2% solution of calcium hydroxide which is the preferred brine used in my method of producing the colloidal clay suspension. It is realized that drilling mud exhibits plastic fiow, and hence the viscosity is a function of the rate of shear. However, the results are comparable, since the various drilling muds were testedunder-identical conditions and the rate ofshearwas maintained constant by operating the Stormer viscometer at 600 R. P. M. The results in centipoises under these condtions were as follows:

. 4% in water 4% in disand treated tilled water with 2 (0 )l Centipoim Cemipolm Florida earth mine A-untreated 3 19 Florida earth mine Apressure treated 9 44 Florida earth mine B-untroated 3 30 Florida earth mine B-pressure trea 8 48 .The table clearly indicates that pressuretreated clay when made into a suspension in water, breaks down into a much finer particle size than can be obtained by fine grinding. Moreove it'will be noted that 200 and finer mesh, material from mine A when placed in water. gave a I viscosity of only 3 centipoises, whereas the same material pressure treated, gave a'viscosity of 9-. centipoises, under-identical conditions. I

The deposit from mine A was considerably better than that from mine B. However, it will be observed from the foregoing table, that the samples of untreated clay from both mines when mixed with distilled water have the same centipoise viscosity, and when pressure treated, the clay from mine A is apoint higher than that from mine B. Further, that when brine is added, the untreated clay from mine A has a viscosity of 19 centipoise's' as compared to 30 centipoises from mine B. When the same clays were pressure treated that from mine A rose to 44 centipoises while that from mine B registered a viscosity of 48 centipoises. In other words, by reason of my improved method, clay deposits which would ordinarily prove unsatisfactory for suspension purposes, may be reclaimed or treated to The samples were further treated provide a very efllcient drilling-mud, which settles out only with thegreatest oi' diiilculty. As

the colloidal suspension may be produced at the] 1 well by the simple expedient oi'mixing the clay with water, in'the proper proportions of each, and then agitating the mixture, it will obviate the necessity of installing an-expensive apparatus either at the well or at a point remote there from to produce the drilling mud. Y

The aqueous mixture, if desired, may have introduced therein any suitable saline material or line as a medium for suspension of the clay such as calcium hydroxide. However, in certain types or character of clay, it will not be necessary to treat the mixture with a brine.

For ordinary practical purposes, the colloidal suspension constituting the mixture may be com- Y posed of 4 parts of fuller's earth or zeolitic clay and 96 parts oi water by weight. This proportion, of course, may be varied depending upon the character of the clay and the constituents of the earthy material where thedrilling operation is to be performed. Y

Theeffects of extrusion on viscosity of fullers earth suspension have been carefully calibrated A with a Stormer viscometer. As a result, it has been established that ordinary unextruded clay shows no increase in viscosity after a long time Y stirring in an ordinary mixer. I When the suspension was transferred to a high speed mixer operating at about 15,000 R. P. M., it resulted in a further increase 'in the viscosity. When extruded fuller's earth is similarly treated, the results are substantially the same exceptthat theviscosity' increases and has uniformly higher values thamthe unextruded material, thus conclusively establishing that extruding the clay accomplishes results which cannot .be obtained by subjecting the suspension to high speed mixing. While it would appear that equal viscositiescould be obtained by long time mixing of extruded clay and unextruded clay when subjected to high speed mixing for extremely long periods of time,

of a 6% suspension of Florida fullers earth when extruded; dried, ground, and activated, were subjected to burning temperatures between 0 and 600 F. These tests show that a maximum viscosity of between 80 and 90 .centipoises is obtained at temperatures in the neighborhood of 200 F., and that as the temperature increases the viscosity proportionately decreases. v

Thus, it will bes'een that my improved method permitsthe-production of a colloidal clay'suspension in which the colloidal properties of Y fullers earth is increased from ten percent to Y three hundred percent measured in terms of viscosity of the aqueous suspension and that the degree of improvement varies in accordance with the particular fuller's earth which is beingtreated or processed.

Hretoforegffuller's earth from only certain mines and possessing certain characteristics has been suitable for producing an aqueous suspension to be used in drilling muds and the like. By reason of the present invention clays from practically all mines can beemployed satisfactorily and rendered suitable .for use as colloidal sus-' pensions.

assuage produced by my method.

While it'was known priorto my invention that the extrusion of rullers earth. aszshown-ifor example in the Hartshorne Patent" No. i2,079,85 4, enhances the absorptive efllciency of ffuller s earth, it was not known that when the colloidal trusion, such extruded'earth maybe dried with out destroying or substantially-reducing the colloidal properties of the suspension so obtained.

Moreover, it was, not previously known that an extruded earth and that when dried,..the product?" so obtained retains its colloidal propertiesand" may be reconverted without further extrusion to an aqueous suspension having colloidal properties of the same order as those initially obtained.

While it might ordinarilybe expected that the extruded earth when subsequently dried would cause-a reduction in the colloidal properties of the suspension, it has been empirically shown that the drying when conducted in' accordance with my process, does not appreciably reduce the colloidal properties of the earth.

It was previously known that fullers earth. when squeezed and kneaded for a suitable period of time in the presence of water will enhance its colloidal properties. However, in such treatment it has been assumed that when the water is removed, the particles will coalesce and may not then be readily suspendedwithout further squeezing and kneading. When the fullers earth is extruded and treated to obtain a colloidal suspension as called for in the present invention, the

time factor is unimportant, and the-pressure is the controlling and essential factor. Thus, it will be seen that subjecting the clay to a rolling,

Y kneading and squeezing action before drying does not obtain the same desirable results as is effected by extruding the clay, since the rolling, kneading and squeezing action will not permit the fullers earth when subsequently dried, to be resuspended without being re-extruded, and therefore will not produce a suspension havinga viscosity of the sameorder as that originally obtained and as The minute particle size resulting from making a colloidal suspension out of pressure treated clay may be utilized to obtain ayery fine and imp-alpable powder by spray drying the colloidal suspension.- By this treatment, a muchfiner mesh can be obtained than by the usual mechanical grinding or reducing means Since the powder has a very high specific surface, it mayjbeefliciently used as a filler in the composition'of various products such as rubber, and to.' replace in part, carbon black and, zinc oxide For certain purposes, it is desired that the particles or powder will not produce; a .eel when mixed with water. In such a case, thissmay be obtained by drying the material either, during the spray drying operationor subsequent to it in another operation, at temperatures above 600 F.,

thus forming a very finely divided clay that will not gel with water. Such a produce may be used in the precipitating bath into which filaments of a cellulose solution are being dispersed'and in general, mayreplace infusorial earth for many of the purposes for which such earth may be It is to be understood that the foregoing method of producing the colloidal clay suspenfall within the purview of one skilled in the art 10 aqueous suspension might be obtained from such colloidal particles, drying the pressure treated and the scope of the appended claims.-

lclaim: 1 An improved method of producing a colloidal cIayfsuSpension for use as a drilling mud which consists in subjectingiullers earth to pressure suili'cie'nt to rupture the original structure of. the earth, drying the pressure treated earth at a ,temperature substantially below 600 F., reducing the earth to granular form, mixing the granular earth, with water, and agitating the mixture to provide a drilling mud.

2. An improved method of producing a colloidal clay suspension for use as a drilling mud, which consists in subjecting fullers earth to pressure suflicient to rupture the original structure of the earth so as to cause each particle to move into a new position relative to the other particles, drying'the pressure treated earth at a temperature substantially below 600 F., reducing the earth to granular form, mixing the granular earth with watenand agitatingthe mixture to provide a drilling mud'which does not easily settle out.

3. An improved method of producing a colloidal clay suspension for use as a drilling mud which consists in subjecting natural moist'fullers earth to pressure-sufficient to rupture the original structure of the earth so as to cause each particle to move into a new position relative to the other earth at a temperature substantially below 600 F., reducing the heated earth to granular form, mixing the granular earth with water, and agitating the mixture to provide a drilling mud.

4. An improved method of producing a colloidal clay suspension'for use as a drilling 'mud which consists in subjecting natural moist fullers earth of the Georgia-Florida type to extrusion under pressure sufilcient to rupture the original structure of the clayso as to cause each particle to move into anew position relative to the'other colloidal particles, drying the pressure-treated clay at a temperature substantially below 600 F., reducing the heated clay to granular form, mixing the granular clay with water, adding brine or salts to the mixture to produce a stable clay suspension, and agitating the mixture to provide a drilling mud which does not easily settle out.

5. The improvedmethod of preparing a material for a colloidal suspension which consists in subjecting fullers earth to pressure under extrusion, drying the pressure treated earth at a temperature not exceeding 250 F.. and then reducing the dried earth.

6. An improved method of producing a colloidal clay suspension which consists in subjecting fullers earth to pressure suflicient to'substantially increase the viscosity of the colloidal suspension as compared with an untreated earth suspension,

drying the pressure treated earth at a temperature in the neighborhood of 200 F., reducing o V I 2,231 without depart ng from the spirit of the invention earth with water, and agitating the mixture.

the earth to granular form, mixing the granular 7. .An improved method of producing a colloidal 4 claysuspension which consists in subjecting full- 'ers earth to pressure suflicient to substantially 5 increasethe viscosity of the colloidal suspension as compared with an untreated earth suspension, and suspending the earth with water.

8. An improved method of producing a colloidal clay suspension which consists in subjecting fullers earth having substantially all of its natural moisture to extrusion under pressure suflicien-t to rupture the original structure or the. clay and change the positions of the colloidal particles, and drying the pressure treated clay at a temperal5 ture substantially below 600 F.

9. An improved vmethod of producing a colloidal clay suspension which consists in subjecting fuller's earth having substantially all of its natural moisture to extrusion under pressure 20 sufllcient to rupture the original structure of the clay and change the positions of the colloidal particles, drying the pressure treated clay at atemperature substantially below 600 F., mixing the clay with' water, and agitating the mixture to provide a colloidal clay suspension of substantiallyincreased viscosity as compared with the viscosity of a clay suspension prepared from the same clay which is not extruded.

10. An improved method of producing a colloidal clay suspension which consists in subjecting fuller's earth having substantially all of its natural moisture to extrusion under pressure sumcient to rupture the original structure of the clay and change the positions of the colloidal particles, drying the pressure treated clay at a temperature in the neighborhood of 200 F., reducing the clay, mixing the reduced clay with water, and agitatingthe mixture to provide a colloidal clay suspensionof substantially increased viscosity as 40 compared with the viscosity of a clay suspension prepared from the same clay which is not extruded.

11. The improved method of preparing a material for a colloidal suspension, which consists 5 in subjecting rullers earth to pressure sufilcient to rupture the original structure of the clay and change the positions of the colloidal particles, mixing the earth with water to provide a colloidal clay suspension of substantially increased viscosity as compared with the viscosity of a suspension prepared from the same clay which is not extruded, and then spray-drying the suspension.

12. As a new article or manufacture, dry fullers earth which has been subjected to extrusion while under pressure on the material sufllcient to -which has not been extruded.

OGDEN FITZ SIMONSV. 

